Prior patents disclose electrical brush contacts intended to have fine wires inserted into a barrel and crimped to comprise the contact. For example, the U.S. Patent of McKeown et al No. 3,725,844 discloses a hermaphroditic electrical contact wherein seven or more brush wires are crimped at one or more points into place within the inner portion of a passage. As suggested therein, the wires could be soldered or brazed into position so long as the wires are in electric circuit relationship with one another. The crimping operation may be performed by a well-known plier type tool that, when squeezed, applies pressure simultaneously to two pairs of diametrically opposed points in the circumference of the contact to conform the contact wall to the wires within the contact.
Each of the contacts and wires associated with such a contact are quite small (the contacts being about one-half of an inch long with a diameter of about 0.060 inches). Generally, electrical contacts are machined from metal stock and, because of their small size, the contacts are machined to tolerances of 0.002 inches or less. A contact which is oversized for any reason cannot be utilized because it may not be possible to insert such a contact into the contact receiving holes in a connector insert or insufficient clearance between contacts could cause electrical and mechanical problems.
Machining of electrical contacts is expensive and because of the large number of contacts utilized by a connector, the connector can be relatively expensive. To reduce the cost of manufacturing a connector and at the same time provide an electrical contact which provides a secure electrical and mechanical connection when the fine wires are crimped within the contact holder, many inventors have turned to making an electrical contact by stamping and rolling (forming) the contact holder from a sheet of metal. For example, the U.S. Patent of Waldron et al No. 4,072,394 discloses a sleeve that is stamped and formed into a tubular shape from a flat sheet of metal.
Other contacts which are stamped and rolled and which are of the type to which this invention relates are disclosed by the U.S. Patents of Narozny et al No. 3,286,223; Henschen et al No. 3,317,887; and Curr No. 3,721,943. In each of the three patents mentioned immediately above, a joint or seam resulted when the contact was formed by rolling flat stock. The seam was then either welded or brazed to prevent the edges of the open seam of the contact from being displaced with respect to each other during a crimping operation. Such crimping operation can cause the end portion of the contact to distort unsymmetrically so it becomes oversized and cannot be properly inserted in its position in an electrical connector.
Therefore, while it is desirable to replace machined contacts with less expensive electrical contacts which are stamped and formed from a sheet of material, the resulting seam prevents the wires from being crimped within the contact unless the seam is brazed or welded. As can be appreciated, brazing or welding seams is very difficult since the longitudinal seam is only a very small part of a contact diameter (about 0.048 inches).
The U.S. Patent of Kleinmann, U.S. Pat. No. 2,093,198 discloses a brush contact for use in tabular machines wherein the wires are firmly held, side by side, in their holders.